JPH0648365B2 - Resin coated paper for photography - Google Patents

Description

The present invention relates to a photographic resin-coated paper, and more particularly to a photographic resin-coated paper having excellent gloss.

Photographic resin-coated paper is already known, for example, as disclosed in U.S. Pat. No. 3,501,298, both sides of a paper substrate are coated with a polyolefin resin, particularly a polyethylene resin, and the polyolefin resin layer on the emulsion coated surface side is made of dioxide. Those containing titanium pigments, coloring pigments, optical brighteners, etc. are well known.

However, in the method for producing photographic resin-coated paper,
The fact is that a resin-coated paper for photographic use having a sufficiently satisfactory glossiness has not yet been obtained.

In recent years, as demand for photographic printing paper has expanded,
Not only experts but also general consumers are not satisfied with the current quality of glossy finish, and the demand for photographic paper with even higher gloss is increasing, and the photographic industry is focusing on improving glossiness. Is the reality.

The glossiness of the finished paper prepared through a series of photographic processing steps after coating the photographic emulsion is the glossiness of the photographic support, that is, the surface of the photographic resin-coated paper (the surface on which the emulsion is coated) if the photographic emulsion is the same. The higher the gloss of the resin-coated paper surface, the higher the gloss of the finished paper tends to be. Therefore,
The photographic support maker is currently making efforts to improve the glossiness of the surface of the photographic resin-coated paper.

The inventors of the present invention have used base paper for base paper of photographic resin-coated paper (usually natural pulp-based paper, synthetic fiber paper,
Synthetic paper) or synthetic resin film surface (emulsion-coated side) has a higher gloss, so long as the resin composition and cooling roll specularity are the same. It was found that the glossiness of the surface (the surface on which the emulsion was applied) also tended to be high.

That is, the present invention relates to a photographic resin-coated paper in which at least one surface of the base paper is coated with a resin composition comprising at least a resin and a titanium dioxide pigment, and at least one surface of the base paper has a pigment and an adhesive. The present invention provides a resin-coated paper for photographic use, which has been coated with a coating composition containing as a main component and then provided with gloss by a gloss imparting machine and has excellent gloss.

The glossiness in the present invention is measured according to JIS P8142, and in the present invention, the glossiness of the surface of the base paper coated with the coating composition is 55% or more, preferably 70% or more. % Or more.

The base paper in the present invention may be a photographic printing paper base paper having a relatively good paper quality, but a normal art base paper made by a relatively poor paper quality acidic, neutral or alkaline papermaking,
Coated base paper and the like are advantageously used.

In the present invention, various inorganic and organic pigments such as clay,
One or more general pigments for coated paper such as talc, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white and plastic pigments are used.

Examples of the adhesive used in the present invention include casein,
Proteins such as soybean protein, extracted proteins from single cell assimilating bacteria such as methanol and acetic acid, gelatins, conjugated diene polymer latex such as styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer, acrylic Acrylic polymer latex such as polymer or copolymer of acid ester and / or methacrylic acid ester, vinyl polymer latex such as ethylene / vinyl acetate copolymer,
Alternatively, an alkali-soluble or alkali-insoluble polymer latex obtained by functionally modifying these various polymers with a functional group-containing monomer such as a carboxyl group, an olefin / maleic anhydride resin, a synthetic resin adhesive such as a melamine resin ,
Common adhesives for coated paper, such as polyvinyl alcohol, positive starch, phosphorylated esterified starch, starches such as oxidized starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, are used alone or in combination.

Further, as an auxiliary agent, an antifoaming agent, a coloring agent, a releasing agent, a fluidity improving agent or the like may be appropriately used if necessary.

The coating composition containing the pigment and the adhesive in the present invention is a blade coater, an air knife coater, a roll coater, a brush coater, a curtain coater, a chanplex coater, a bar coater, and a gravure which are used in general coated paper production. The base paper is coated in one layer or in multiple layers by an on-machine or off-machine coater provided with a coating device such as a coater or a size press coater.

The coating amount on at least one surface is 2 to 2 in terms of dry weight.
It is about 50 g / m ² , and the larger the coating amount, the better the glossiness of the resin-coated paper for photographic use, but the range of 5 to 35 g / m ² is preferable from the viewpoint of operability and quality. is there.

In this manner, the matte base paper obtained by coating the base paper with the coating composition is then used as a base paper for the photographic resin-coated paper after being gloss-applied by various glossing machines, for example, a super calendar. .

The coated paper is usually coated on one surface of the base paper, but it may be coated on both surfaces in consideration of curl balance and the like.

As the thermoplastic resin used in the resin layer of the photographic resin-coated paper in the present invention, polyolefin, polystyrene,
Homopolymers or copolymers of polyvinyl chloride, polyacrylic esters, linear polyesters such as polyethylene terephthalate, polycarbonates, polyamides such as nylon, cellulose esters, polyacrylonitrile, such as ethylene-vinyl acetate copolymers and mixtures thereof. Any resin can be used as long as it can be coated with a resin film on the base paper, but in particular, polyolefin, polystyrene, polyethylene terephthalate,
Thermoplastic resins such as polyvinyl chloride are preferable, and among them, polyolefin resins are particularly advantageous in terms of extrusion coating properties, good adhesion to base paper, cost, and the like. The polyolefin resin in the present invention means a homopolymer of low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutene, polypentene or the like, or a copolymer composed of two or more olefins such as ethylene-propylene copolymer and the like. , Which have various densities and melt viscosity indexes (melt indexes: hereinafter simply abbreviated as MI), can be used alone or as a mixture thereof. Further, linear low density polyethylene, which is a copolymer of ethylene and α-olefin, and a mixture of these and various polyolefins can also be used.

The masterbatch used in the resin layer of the photographic resin-coated paper in the present invention is a commonly used melt-kneading machine,
For example, Banbury mixer, kneader, 2 rolls, 3
It is produced by the present roll, an extruder for kneading, etc., but it is particularly advantageous to use a Banbury mixer. If necessary, these kneading machines may be used in combination.

The titanium dioxide pigment used in the practice of the present invention,
Either the rutile type or the anatase type can be used, but it is advantageous to use the anatase type from the viewpoint of whiteness. Further, titanium dioxide may be so-called untreated titanium dioxide which is not surface-treated at all, or may be surface-treated with various organic surface treatment agents such as various alcohols, surfactants, siloxanes and silane coupling agents. Or various inorganic surface treatment agents such as hydrous aluminum oxide, hydrous silicon oxide, hydrous titanium oxide, hydrous zirconium oxide, zinc hydroxide, magnesium hydroxide, manganese compounds, phosphoric acid compounds and combinations of several of these. It may be a so-called inorganic surface-treated titanium dioxide that has been surface-treated with.

The treatment amount of these inorganic surface treatment agents is preferably 0.2 to 1.2% by weight (calculated in the form of anhydride), and particularly preferably 0.2 to 0.6% by weight, based on titanium dioxide.

The inorganic surface treatment agent for titanium dioxide used in the practice of the present invention is preferably hydrous aluminum oxide, and its treatment amount is 0.2 to 1.2% by weight (Al
₍ Calculated in the form of ₂ O ₃ ) is preferred, with 0.2 to 0.6% by weight being particularly preferred.

The masterbatch used in the resin layer of the photographic resin-coated paper in the present invention preferably contains a fatty acid metal salt.

Examples of these fatty acid metal salts include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, sodium laurate and the like. Further, the addition amount thereof is preferably in the range of 0.01% by weight to 5% by weight with respect to the resin composition containing titanium dioxide.

The masterbatch used in the present invention preferably further contains an antioxidant, particularly a hindered phenolic antioxidant.

Examples of the hindered phenolic antioxidant include 1.
3.5-trimethyl-2.4.6-tris (3.5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene (3.5-di-tert-butyl-4-hydroxy-hydrocinnamate)] methane, Octadecyl-3.5
-Di-tert-butyl-4-hydroxy-hydrocinnamate, 2.2 '. 2 "Tris [3.5-di-tert-butyl-4
-Hydroxyphenyl) propionyloxy] ethyl isocyanurate, 1.3.5-tris (4-tert-butyl-
3-Hydroxy-2.6-di-methylbenzyl) isocyanurate, tetrakis (2.4-di-tert-butylphenyl) 4.4'-biphenylene diphosphite, 4.4'-
Thiobis- (6-tert) -butyl-O-cresol),
2.2'-thiobis- (6-tert-butyl-4-methylphenol), tris- (2-methyl-4-hydroxy-)
5-tert-butylphenyl) butane, 2.2 'methylene-
Bis- (4-methyl-6-tert-butylphenol),
4.4'-methylene-bis- (2.6-di-tert-butylphenol), 4.4'-butylidenebis- (3-methyl-6)
-Tert-butylphenol), 2.6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2.
6-di-tert-butylphenol, 2.6-di-tert-butylphenol, 2.6-di-tert-butyl-4-n-butylphenol and the like can be mentioned. Further, two or more kinds of antioxidants may be used in combination depending on the characteristics of the antioxidant. The content of the antioxidant in the masterbatch is 5 to 250 ppm, preferably 5 to 150 ppm, more preferably 5 to 100 ppm in 100 parts by weight of the resin composition.

In the masterbatch used in the present invention, in addition to the fatty acid metal salt, if necessary, zinc oxide, talc, white pigments such as calcium carbonate, stearic acid amide, fatty acid amides such as arachidic acid amide, cobalt blue, Color pigments such as dark blue, ultramarine blue, cobalt violet, and fluorescent whitening agents may be added.

To make a resin-coated paper for photography, so-called solvent coating in which a resin is dissolved in a solvent to coat it on the base paper surface, or a laminating method in which a resin film is attached to the base paper surface can also be used. The resin-coated paper is manufactured by subjecting a resin composition containing a titanium dioxide pigment, which has been heated and melted, to a base paper that is normally running, by film-shaped melt extrusion coating from a slit die. When the resin is a polyolefin resin, the melt extrusion temperature is 200 ° C
It is preferably from to 350 ° C. Further, it is preferable that the base paper is subjected to an activation treatment such as a corona discharge treatment or a flame treatment before the resin composition is melt-extrusion coated onto the base paper. The thickness of the resin layer of the resin-coated paper is not particularly limited,
Generally, extrusion coating having a thickness of about 5 to 50 microns is advantageous. In addition, in a normal resin-coated paper in which both sides of the base paper are coated with a resin, the resin surface containing the titanium dioxide pigment has a glossy surface depending on the application,
It has a matte surface, a matte surface, etc., and the back surface on the opposite side is usually a matte surface, and the front surface or both surfaces may be subjected to activation treatment such as corona discharge treatment or flame treatment, if necessary.

The base material as the base paper used in the practice of the present invention may be any of ordinary natural pulp paper, synthetic fiber paper, synthetic paper or synthetic resin film, but the main component is wood pulp of softwood pulp, hardwood pulp, mixed wood of hardwood and hardwood. The natural pulp paper is preferably used. The thickness of the base paper is not particularly limited, but the basis weight is 50 to 350 g /
m ² is preferred.

In the present invention, these natural pulps include rosin, soap, wax, sizing agents such as synthetic sizing agents, bands, fixing agents such as aluminum chloride, and fillers such as clay, talc and calcium carbonate for ordinary arts. When a photographic resin-coated paper is produced by using a base paper, a base paper for coating, etc. as a substrate and using the coated paper having a gloss finish according to the present invention as a base paper, a paper having excellent glossiness can be obtained.

Of course, even when a photographic printing paper is used as the substrate,
A photographic resin-coated paper having excellent glossiness can be obtained.

The base paper for photographic printing paper used in the present invention may contain various polymer compounds and additives. For example, as a dry paper strengthening agent, cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin and the like, and as a sizing agent, fatty acid salt, rosin derivative, dialkylketene dimer emulsion, petroleum resin emulsion , Styrene-maleic anhydride copolymer alkyl ester ammonium salt, etc. as pigment, clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, etc., wet paper strength enhancer, melamine resin, urea resin, epoxidized polyamide resin , Fixing agents such as aluminum sulfate, polyvalent metal salts such as aluminum chloride, cation-modified polymers such as cationized starch, etc., pH adjusting agents such as caustic soda, sodium carbonate, hydrochloric acid, etc., inorganic electrolytes such as salt, mirabilite, etc. Other dyes can be incorporated in combination optical brightener, latex and the like appropriate. Various silver halide photographic emulsion layers can be provided on the photographic resin-coated paper of the present invention. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided.

Further, a color coupler may be incorporated in the silver halide photographic emulsion layer to provide a multilayer silver halide photographic constituent layer. As a binder for these silver halide emulsion layers, in addition to ordinary gelatin, hydrophilic polymer substances such as polyvinylpyrrolidone, polyvinyl alcohol, and sulfate ester compounds of polysaccharides can be used. Further, the silver halide emulsion layer may contain various additives. For example, as sensitizing dyes, cyanine dyes, merocyanine dyes, etc., as water-soluble gold compounds as chemical sensitizers, sulfur compounds, etc., as antifoggants or stabilizers, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc. , As hardener, formalin, vinyl sulfone compound, aziridine compound, etc., as coating aid, benzene sulfonate, sulfosuccinate salt, etc., as antifouling agent, dialkyl hydroquinone compound, etc., development accelerator, hydroquinone, phenidone, etc. As a UV absorber, a benzotriazole compound, etc., as well as a fluorescent whitening agent, a sharpness improving dye, an antistatic agent, a pH adjusting agent, and a water-soluble iridium compound, a water-soluble rhodium compound, etc. at the time of producing and dispersing silver halide are appropriately used. In combination It can be allowed to Yes.

Further, on the back surface of the photographic resin-coated paper according to the present invention, that is, on the surface of the support opposite to the surface on which the photographic constituent layer, mostly a silver halide photographic constituent layer, is coated, anti-curl, antistatic, A coating layer composed of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing tackiness and slipping. The back coat layer may contain a binder or protective colloid, a curing agent, an antistatic agent, a surfactant, a matting agent, latex and the like.

Next, examples will be described to more specifically describe the present invention.

Example 1 70 parts by weight of kaolin, 30 parts by weight of light calcium carbonate and 0.5 parts by weight of sodium polyacrylate were dispersed in water using a Choles disperser to prepare a pigment slurry having a solid content concentration of 60%. Styrene butadiene latex 10
Parts (solid content) and 5 parts (solid content) of oxidized starch made from cornstarch as a raw material, and sufficiently stirred to obtain a coating liquid (A
As a liquid).

Separately, 100 parts by weight of kaolin and 0.2 parts by weight of sodium pyrophosphate were dispersed in water using a Choles disperser to prepare a pigment slurry having a solid content of 70%. To this, 12 parts (solid content) of butadiene-methylmethacrylate copolymer latex and 1 part (solid content) of phosphoric acid esterified starch made from cornstarch were added and sufficiently stirred to obtain a coating liquid (B liquid and To).

Next, 50 parts by weight of kaolin, 50 parts by weight of light calcium carbonate and 0.5 parts by weight of sodium polyacrylate were dispersed in water using a Choles disperser to prepare a pigment slurry having a solid content concentration of 60%. To this, 7 parts (solid content) of styrene-butadiene latex and 4 minutes (solid content) of oxidized starch made from cornstarch were added and sufficiently stirred to obtain a coating liquid (referred to as liquid C).

These coating liquids are coated on the base paper for the art with an air knife coater for the liquid A, and with the blade coater for the liquid C on the base paper for art or photographic printing paper, and then the liquid B on the base paper with an air knife coater. After applying the combinations as shown in Table 1, gloss was imparted by a super calendar. Incidentally, C
The coating amount ratio of the liquid and the liquid B was 1: 1 respectively. The results of measuring the glossiness of these base papers are shown in Table 1.

Next, high-density polyethylene (MI = 7, density 0.96 g / cm ³ ) was applied to the back surface of these base papers while corona discharge treatment was applied.
And low density polyethylene (MI = 3, density 0.92 g / c
A 1: 1 mixture of m ³ ) was applied at a resin temperature of 320 ° C. using a melt extruder to a thickness of 30 μ.

Then, the surface of the base paper (the surface coated with the coating composition) was subjected to corona discharge treatment while masterbatch 20 parts by weight, high density polyethylene (MI = 7, density 0.96 g / cm ³ ) 2
0 parts by weight and low density polyethylene (MI = 5, density 0.9)
A resin composition containing 60 parts by weight of 2 g / cm ³ ) was applied at a resin temperature of 320 ° C. to a thickness of 30 μm to produce a polyethylene resin-coated paper containing a pigment of titanium dioxide. At that time, the surface of polyethylene containing the titanium dioxide pigment was processed into a completely flat glossy surface, and the surface quality of polyethylene on the back surface was processed into a matte surface such as paper. For comparison, a resin-coated paper for photographic use was also prepared in which resin was coated on the front and back sides in the same manner as described above on the base paper for art and photographic paper.

Corona discharge treatment was performed on the resin surface containing titanium dioxide of the eight kinds of photographic resin-coated papers including the comparative ones thus obtained, and the emulsion for color photographic paper was coated. The glossiness of the photographic paper thus obtained was visually judged and evaluated as excellent ⊚, good ∘, slightly bad Δ, and bad x.

The results obtained are shown in Table 1.

The masterbatch, the base paper for art, and the base paper for photographic printing paper were prepared as follows.

<Masterbatch> low density polyethylene (MI = 7, density 0.92 g / cm ³⁾
50 parts by weight, 50 parts by weight of hydrous aluminum oxide treated anatase type titanium dioxide (0.5% by weight calculated in the form of Al ₂ O ₃ to titanium dioxide), 2 parts by weight of zinc stearate and
3.5-di-tert-butyl-4-hydroxy-hydrocinnamate (100 ppm) was placed in a Banbury mixer and well kneaded at 150 ° C to obtain a masterbatch.

<Art base paper> 0.6 part by weight of rosin size to 100 parts by weight of pulp,
8 parts by weight of filler (clay: talc = 4: 6), sulfuric acid band
An art base paper having a basis weight of 100 g / m ₂ consisting of 1.2 parts by weight and a surface size (liquid of 4% solid content of oxidized starch made from corn starch) was used.

<Base paper for photographic printing paper> To 100 parts by weight of pulp, 3 parts by weight of cationized starch, 0.2 part by weight of anionized polyacrylamide, and emulsion of alkyl ketene dimer (as ketene dimer content).
4 parts by weight and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin were added for papermaking. Sequentially 3 parts by weight of carboxy-modified polyvinyl alcohol, optical brightener 0.05
The base paper for photographic printing paper was used which was impregnated with an impregnating solution consisting of 0.002 parts by weight of blue dye, 0.2 parts by weight of citric acid and 97 parts by weight of water, dried with hot air, and calendered.

Claims (3)

[Claims] 1. A photographic resin-coated paper in which at least one surface of a base paper is coated with a resin composition comprising at least a resin and a titanium dioxide pigment, wherein at least one surface of the base paper has a pigment and an adhesive. A resin-coated paper for photographic use, which has been coated with a coating composition containing as a main component and then provided with gloss by a gloss imparting machine. 2. The photographic resin-coated paper according to claim 1, wherein the gloss imparting machine is a super calendar. 3. The photographic resin-coated paper according to claim 1, wherein the gloss-imparted surface of the base paper coated with the coating composition has a glossiness of 55% or more.